Solar maximum

 

Our sun is perturbed. It’s throwing off huge flares and erupting with spots like a teenager. That’s because this year marks the “solar maximum”–and that could mean trouble on Earth.

The discovery of sunspots coincided with the invention of the telescope. Galileo was quick to turn his on the sun, focusing the image on a white surface. To his astonishment, he saw dark blotches that moved and changed. The sun was not constant!

Galileo didn’t publish his discovery for a long time; following up his claim that the Earth moved around the sun with one that the sun wasn’t perfect would not have been a good career move. The first person to actually publish findings concerning sunspots was the German scientist Johannes Fabricius, in 1611.

Sunspots became favorite targets of astronomers. A Jesuit monk named Christopher Scheiner wrote a 784-book (in Latin!) about them in 1630, which is pretty amazing considering nobody had the faintest idea what they were. Theories ranged from dark clouds over a bright surface to dark holes in bright clouds.

Today, we know that sunspots aren’t really black, they just look that way because, at 4,000 degrees Celsius, they’re 2,000 degrees cooler than the normal surface of the sun. We also know sunspots have magnetic fields about 10,000 times stronger than Earth’s.

We don’t know why they form. One theory is that because different parts of the sun rotate at different speeds, the lines of force in its magnetic field get twisted and develop kinks that erupt through the surface as sunspots.

Sunspots peak every 11 years during the solar maximum, coinciding with an increase in solar flares (explosive expulsions of matter) and the solar wind (bits of solar material that stream throughout the solar system all the time). All of this activity could spell trouble.

When a solar flare hits a satellite, charged particles build up on its outside, and more powerful radiation can penetrate deep inside, damaging circuitry. In 1998 a solar storm knocked out the Galaxy 4 satellite, silencing 80 percent of North America’s pagers, knocking financial services offline and stopping credit-card transactions.

Solar flares can cause damage on the ground, as well. An intense solar flare in March of 1989 blacked out all of Quebec, putting six million people in the dark for nine hours. Auroras danced in the sky as far south as the Caribbean.

Astronauts in orbit could receive dangerous levels of radiation exposure, and aircraft crew and frequent fliers on polar routes could receive higher-than-normal doses, too.

The National Oceanic and Atmospheric Administration in the U.S recently established three scales that measure the severity of a solar storm in terms of its potential for geomagnetic disruption (G), increased solar radiation (S) and radio blackouts (R). Each scale uses a 1-5 numbering system.

A G5 storm could cause the collapse of power grids and damage to electrical transformers, interfere with satellite and high-frequency radio communication, degrade the Global Positioning System and other navigational systems and result in northern lights being seen at the equator.

An S5 storm could pose a high radiation hazard to spacewalkers and expose passengers in high-altitude planes at high latitudes to the equivalent of a chest X-ray. Some satellites could be lost or damaged, no high-frequency communications would be possible in polar regions, and all navigational operations that depend on radio communication could be extremely difficult.

An R5 storm could produce an hours-long blackout of all high-frequency radio–the kind used by aviators and maritimers–on the entire sunlit side of the Earth.

NOAA now offers a regular space weather forecast, complete with alerts and warnings, on its website at www.noaa.gov. Our increasing dependence on satellites and wireless communication will make accurate space weather forecasts more and more important over the next few years.

In preparation for the current solar maximum, NASA launched the Advanced Composition Explorer, which orbits 1.6 million kilometres from Earth to provide early warning (about 45 minutes) of solar flares. On March 15, NASA will launch IMAGE (Imager for Magnetopause-to-Aurora Global Exploratio), to study how Earth’s magnetic field reacts to changes in the solar wind. Another upcoming mission, STEREO (Solar-Terrestrial Relations Observatory) will make 3D images of large solar flares.

NASA is also proposing a decade-long initiative, “Living With a Star,” which would study the side of the sun facing away from the Earth, analyze the activity beneath the sun’s surface, and place “space buoys” in orbit to monitor the impact of solar storms on Earth’s upper atmosphere.

When you’re living next to an unruly neighbor, you want to keep a close eye on him.

Permanent link to this article: https://edwardwillett.com/2000/03/solar-maximum/

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